I am fan of Debian GNU/Linux wheezy and I am using three different browser’s (Iceweasel, Firefox, Chrome) for various reasons. If you want to enable Java plugin for all those three browsers, then there is a single action that can do the work for you.

First of all you have to install a JRE, in order to have a VM environment for your browser. This could be provided by SUN (now Oracle) JRE 6 or 7 , or OpendJDK 6 or 7. If you have installed any of these, then you have to locate the location of the required library (for Oracle JRE is the “libnpjp2.so” file) and create a symbolic link to this.

As you can see I use Oracle JDK 6 (1.6.0_26), which I have downloaded from Oracle and just extracted to directory “/opt/myjdks/”.

You can do it with one command, but I split them to two separate commands to be more readable.

If you have installed Firefox as me (downloaded from Mozilla and just extracted somewhere and using a different profile in order to use Firefox and Iceweasel concurrently), then this Firefox will use this plugin too.

UPDATE: 16/2/2014
It is very easy to install Java plugin in your browser, using package icedtea-7-plugin.
In a Debian like system, just run this as root:$> apt-get install icedtea-7-plugin
This will install web browser plugin based on OpenJDK 7 and IcedTea.

Wheezy in original browser (Iceweasel 17.09)
First i sent /home/usr/.mozilla/plugins/libnpjp2.so to the trash.(Im not sure if necessary)
Then i download jre-7u45-linux-x64.tar.gz [from Java page of course :)]….
So i made a java file in this way: #mkdir /usr/java
I moved the jre-7u45-linux-x64.tar.gz like this: #mv /usr/Downloads/jre-7u45-linux-x64.tar.gz /usr/java
Into the java file (cd /usr/java) i made this way:#tar zxvf jre-7u45-linux-x64.tar.gz
To finish this command: # ln -s /usr/lib64/jvm/jre1.7.0_45/lib/amd64/libnpjp2.so /home/usr/.mozilla/plugins
Close the Iceweasel and when open again you can make java test…
See you…